Signal decoder with digital to analog. Digital signal

Specifications:

· Includes professional and easy-to-use software: ULead Video Studio 8.0 SE DVD.

· USB 2.0 interface

· Video and sound capture

· Brightness control, contrast, saturation and color

· Small size

· Plug & Play

· Support for all formats: Record DVD +/- R / RW, DVD +/- VR, and DVD-Video.

· Can be used for video conferencing

· Complies with USB 2.0 specification.

· Support for NTSC formats, PAL, VIDEO Format.

· Video input: one composite RCA, one s-video.

· Audio input: StereoVuk 2 RCA

· Dimensions: 88mm * 28mm * 18mm.

· Supported resolution: NTSC: 720 * [Email Protected] PAL: 720 * [Email Protected]

System requirements:

· Free USB 2.0 port

· Windows 2000 / XP / Vista32bit

· CPU Pentium ⅲ 800

· 600MB free disk space for installation by

· 4GB and more free disk space to capture video and edit.

· Memory: 256MB RAM.

· Display: minimum 1024 * 768.

· Sound card

Contents of delivery:

· 1 x Easycap USB 2.0 video audio video capture adapter

· 1 x USB cable

· 1 x CD-ROM (Software)

Another interesting application for EasyCAP device is an image record from the Web camera. So the computer turns into a video surveillance device. This is a very inexpensive solution can be used for personal home or professional purposes.

At the end, I would like to say that the purchase of EasyCAP device is advisable if you are going to digitize more than 5 videos of VHS format. If your video archive is less, it will be cheaper to order overwriting video on DVD in the photo center.

Hello everyone.

In today's review, we will talk about an audio converter that converts a digital signal to analog.

With the development of technologies, our habits and needs, unfortunately, are not going anywhere. So I, having changed the old TV to a more progressive model, discovered with sadness that there is no 3.5 mm connector in it for connecting headphones or other acoustics. And since before that, I was connected to the TV audio system 2.1, devoid of digital connectors and stop using it in the future I did not plan, since her sound was fully satisfied, then the question arose about the way it was connected. In addition, sometimes I connect headphones to the TV so that the loud sounds are not walked by other members of my family.

After studying the possible options, it became clear that the easiest and most logical way to solve my problem would be to buy a converter capable of turning the digital sound into analog. Fortunately, there are no problems with such converters and anyone can choose a converter equipped with the necessary connectors.

Before placing the order, in order to maximize the transaction, it was decided to check the seller using the local service. The test results showed that the seller is reliable and can be trusted. Detailed data obtained as a result of testing can be viewed.

The parcel was sent quickly quickly and in the way spent about a month. Information about tracking the parcel anyone can see.

A converter is supplied without any original packaging, my instance came in a regular polyethylene package. Despite the fact that in addition to the thin layer of the puzzle, the contents of the parcel did not protect anything, during the trip, its contents did not suffer. So, in the package of delivery, in addition to the most converter were: instructions, a network adapter on 1a, a power cable with a length of about 1 meter, as well as a cable Optical cable 1.5 meters long.

Such a set is enough to ensure that the converter can immediately use. Do not buy anything.

The instruction is printed in English, the size of the A5 format sheet.


In principle, there is nothing particularly interesting here. If only the technical characteristics of the converter.

The converter itself is a small box with multiple connectors on each side. On its top there is information about what it is and from which side connectors running on "Login", and with what "output". The size of the converter is quite compact - 50 * 40 * 26 mm., So you can throw it for the TV, where it will not be visible and will not attract attention.


From the opposite side - everyone is well-known inscription "Made in China", as well as a couple of icons and the assertion that this equipment complies with the requirements of the ROHS directive limiting the content of harmful substances.


The converter itself is made qualitatively. Inside nothing hangs, does not rattle. When compressed, the case does not crack. The gaps, gaps or something like this was found. Outsair smell of plastic is also not.

So, from the "input" there are 3 connector: fiber-optic Toslink, coaxial, as well as a power connector. I'm looking forward to say that I immediately postponed a complete network adapter. The converter works perfectly from USB connector to 1A available on TV. In addition, no, no, and the saving of electricity, the converter works only when the TV is turned on.


From the "output" as there are several connectors: a pair of RCA "tulips", 3.5 mm minijack, as well as an indication LED that informs us about the state of the converter: during its operation it glows red.


There is nothing more interesting in the appearance of the converter, which means you can move to its practical tests. To begin with, we use the Toslink complete cable and connect the converter to the network.


It can be seen that the red diode located on the converter lit up. In the same way, the cable itself is glowing in red, which indicates that everything works in normal mode. By connecting the fiber-optic cable into the converter on the other hand, and with the other by stuck in it 3.5 mm. Audio connector, I first did not hear anything: (but then it came to me that you need to select the desired source of sound in the TV settings. After that, everything worked as it should.

Now about the most important thing - about working capacity. The converter works fine. No noise, wheezing, squeaks and other unpleasant sounds were heard. Moreover, it is equally refer to both the sounds in the headphones and to the audio system 2.1. The sound itself is loud and clear. No worse than I had before it was on the old TV when connecting through a standard 3.5 mm. connector. What else liked it is something that the possibility of simultaneously connecting several gadgets is implemented. That is, one can be connected via "tulips", and the second after 3.5 mm. connector. So do not constantly switch the wires.


Summing up all that it was written here, I can say that I liked the converter and I consider the purchase of successful. Everything works exactly as it should. There were no problems with connecting or setting. So if you have in the TV as exclusively "digital" audio connections, you can draw your eyes to a similar product - it will again help you to hear the sound in headphones :) Although, to be honest, I am not very clear to the desire of manufacturers to get rid of "analog "Outputs ...

On this, perhaps, everything. Thank you for your attention and spent time.

DAC - digital analog converter - needed to convert the audio signal from a digital format to analog; Usually, for transmission to an amplifier or immediate sound.

All modern audio recording formats use a digital representation. And tracks on CD or Blu-ray drives, and MP3 files, and music from iTunes - all are stored in a digital format. And in order to reproduce this entry, it must be converted to an analog signal - this function and performs a digital-analog converter. The built-in DAC is present in any device reproducing music. But it often happens that the quality of playing the same audio files (or tracks from the same disk) on different players is noticeably different. If the same amplifiers and headphones are used, it means that the problem is in the player DAC.

Dacaps are different: cheap low power converters (frequently used manufacturers in mobile devices) have low speed and low bit, which is strongly affected by sound quality.

If a mobile device has a digital output (S / PDIF or USB), you can connect an external DSA to it - it guarantees the high quality of digital sound conversion into analog.

In addition, the external DAC may be very useful when listening to music recorded in Loseless-formats (audio recording formats without loss of quality) with high discretion, providing the maximum semblance of recording and the original. Since such entries are distributed, mostly via the Internet, they often liste them directly from the computer. But a high-quality sound card is rarely found on laptops and tablets, and the sound cards built into the motherboard are not highlighted in high quality. And in this case, the whole point of listening to Loseless music is lost absolutely. The situation can be corrected if there is a digital audio output on the computer, for example, S / PDIF. By connecting a DAC with a sampling frequency and a bit no less than that of the recorded recording, you can get an analog signal of high quality.

Another nice bonus can be obtained by purchasing a DAC with Bluetooth support. This will allow you to listen to excellent music on the speakers connected to the converter, without being "tied" to it with wires. For a mobile computer (tablet or laptop) it may be very convenient. In addition, with such a converter, you can play music from other devices that support Bluetooth and easily switch between them.

ADC - Analog-Digital Converter - Needed, on the contrary, to convert an analog audio signal into a digital format. The ADC will be indispensable for digitizing (translated into a digital format) of old analog records: on records, audio and video tags. Also, the ADC will be required when recording in digital form "live" sound from the microphone. Players with recording function and computer sound cards have a built-in ADC, but if the quality of digitization is important to you, it is better to entrust this task to a specialized device.

Despite completely opposite tasks, the ADC and DAC have some common characteristics that have a great influence on the quality of the conversion.

Characteristics of audio converters.

For ADC sampling frequency Determines which frequency the converter will measure the amplitude of the analog signal and transmit it in digital form. For the DAC, on the contrary, with what frequency digital data will be converted into an analog signal.

The higher the sampling rate, the result the conversion is closer to the source signal. It would seem that the higher this indicator is the better. But, according to the Kotelnikov Theorem, to transmit a signal of any frequency, the sampling frequency is sufficiently greater frequency of the signal itself. With the fact that the highest frequency distinguishable for rumor is 20 kHz (most people have the upper limit of audio sound in the area of \u200b\u200b15-18 kHz), sampling frequencies in 40 kHz should be sufficient for high-quality digitization of any sound. Discretization frequency Audio CD: 44.1 kHz, and the maximum sampling frequency MP-3 files: 48 kHz, selected just based on this criterion. Accordingly, the DAC, which loses audio and MP3 files must have a sampling frequency of at least 48 kHz, otherwise the sound will be distorted.

Theoretically, this sampling frequency should be sufficient, but almost sometimes there is a need for greater frequency: the real audio signal does not fully meet the requirements of the Kotelnikov Theorem and under certain conditions the signal may be distorted. Therefore, connoisseurs of pure sound are popular with a 96 kHz discretization frequency.

The sampling frequency of the DAC is higher than that of the source file, the sound quality does not affect the quality of the sound, so it makes sense only if you are going to listen to Blu-ray and DVD-audio or Loseless music with a frequency of sampling with it. Large 48 kHz.

If you firmly aimed at the acquisition of a converter with a sampling frequency above 48 kHz, it is not worth saving on the purchase. DAC, like any other audio device, adds its own noise to the signal. In low-cost models, noise can be quite high, and taking into account the high frequency of sampling, a dangerous ultrasonic noise may appear at the output of such a converter. Yes, and in the hearing range, noity may turn out to be so high that it overshadows the whole gain from increasing the frequency of sampling.

Bigness- The second characteristic that directly affects the quality of the conversion.

The discharge of the DAC should correspond to the audio file's discharge. If the discharge of the DAC will be lower, it is likely to simply be able to convert this file.

The Audio CD tracks have a bit of 16 bits. This implies 65536 gradations of amplitude - in most cases this is sufficient. But theoretically, in ideal conditions, the human ear can provide greater permission. And if the difference between the records with 96 kHz and 48 kHz and 48 kHz can argue, then distinguish a 16-bit sound from 24-bit in the absence of background noise can many people with good hearing. Therefore, if the DAC is supposed to be used to listen to the DVD and Blu-Ray audio, you should select a model with a bit 24.

The higher the discharge of the ADC, the more accuracy the amplitude of the audio signal is measured.

When choosing the ADC, it should be processed from what tasks with it is assumed to be addressed: for digitizing "noisy" audio recordings from old tapes, high-digit ADC is not needed. If you plan to get a high-quality digital record from the studio microphone, it makes sense to use a 24-bit ADC.

Number of channelsdetermines which sound will be able to convert the device. A two-channel converter will be able to handle stereo and mono sound. But to convert the Dolby Digital or Dolby TrueHD signal, a six-or-eight-channel converter will be needed.

Signal / noise ratio Determines the noise level added to the signal by the converter. The higher this indicator, the more clean the signal passing through the converter remains. To listen to music, it is undesirable that this indicator be below 75 dB. Hi-Fi equipment provides minimum of 90 dB, and high-quality Hi-End devices are capable of providing a signal-to-noise ratio of 110-120 dB and higher.

DAC should have a digital entrance- It can be S / PDIF, USB or Bluetooth. OutputdAC Analog - "Jack" (Jack) or "Tulips" (RCA). At the ADC, the opposite is the analog input and digital output. Well, if the converter has several different inputs and outputs - it extends the capabilities to connect to it from various devices. If the input on the converter is one, make sure that the similar output is on the device to which it is assumed to be connected.

Audio converters are more likely to studio and home equipment, so foodmost converters are made from a 220V network. But there are also converters that feed from batteries and can be used autonomously. This may be convenient when using a transducer with a mobile device - a laptop, a tablet, a smartphone or player.

Some converters are powered through the Micro-USB connector, and they cannot receive an audio signal through this connector. If it is important for you that the DAC can read audio files on USB media, before purchase, make sure that the USB on the device is used not only to power.

Selection options.

If you need a device with which you can digitize old tape recorders or write to a computer sound from the microphone, you need an analog-to-digital converter. Prices for them start from 1100 rubles.

If you want to get a device for high-quality playback of audifiles from a smartphone with a wireless connection, choose among the DAC with Bluetooth support. Such a device will cost you 1400-1800 rubles.

If you wish to hear all the wealth of sound recorded in Loseless-format with a high frequency of sampling and a bit rate of 24, you will need the corresponding DAC. It will cost from 1,700 rubles.

Modern digital devices for the knowledge of our analog world use analog-digital converters. About how it works, I will tell you in this article.

If the continuous signal needs to be in a digital form, the analog input value must be converted to the corresponding number. This task is performed an analog-digital converter (ADC or ADC).

Theory

S (T) is some mathematical function that describes our signal. It is impossible to choose a simple popular function as for a sinusoidal signal. Therefore, we will not leave S (T). However, in mathematics it is proved that almost any function can be represented as the sum of sinusoidal (SIN and COS) signals, but with different amplitudes and angular frequencies. And the more difficult the function, the more sinusoidal signals it is necessary. As a result, we get:

Sinuses and cosines in this amount are called the harmonics of the signal S (T) and they are spectrum Signal S (T), and the sum is called near Fourier. This is the foundation of spectral analysis, which is widely used in modern techniques. Signal spectrum (SIN and COS set) is convenient to portray in the form of a graph, for example, for sinusoidal:

(The mirror part appears only because of mathematical transformations, there is no physical meaning)
And for our signal:

The procedure for analog-to-digital conversion of continuous signals, which is implemented using ADC, is a conversion of the continuous function of the time S (T), which describes our signal into the sequence of numbers S1, S2, S3, S4 ..., attributed to some fixed time. This procedure can be divided into two independent operations. The first one is called discretization And it consists in converting the continuous function of the time S (T) into the continuous sequence S1, S2, S3, S4 .... The second is called quantization and consists in converting a continuous sequence in discrete S1 *, S2 *, S3 *, S4 * ...

The sampling of continuous signals is based on theorem references (Whitaker Theorem - Nyquist - Kotelnikova - Shannon):

If there is a S (T) signal, the spectrum of which does not contain the frequency above the FMAX, then it can be completely restored if the s (t) s (t) are known to be taken at equal intervals:

According to this theorem, to represent an analog signal in digital form, we need references. But then the problem: the real signals have an endless spectrum and there are no real signals. In this case, it is necessary to trim the spectrum of the signal using the filter, so we are artificially creating. It is usually taken in such a spectrum site where the level of amplitudes harmonic does not exceed 10% of the maximum value. Call top frequency spectrum. It is also appropriate to talk about the upper angular frequency of the spectrum.

The use of sampling for our signal leads to the emergence of specific high-frequency distortion, due to the sample in the processing systems. To reduce these distortion, it is necessary to either increase the sampling frequency, or take more. However, the information containment of the signal increases. It is often superfluous, and in any practical task you should look for the "golden middle".

Ultimately, our analog signal will correspond to a set of references, of which the signal can be restored like this:

When the signal quantization also loses the loss of information due to the final set of signal levels, which also affect the information container of the digitized signal.

Summary:

1. Signals can be studied both in the time domain and in the frequency (spectrum).
2. To get a digital signal from the analog signal, you must first discretize it, and then quantize.
3. To sampling the signal, you need to limit its spectrum.
4. It is necessary to optimally choose the sampling frequency and the number of quantization levels.
5. When sampling, we constantly round analog value to the nearest digital and in the end we have errors - noise sampling.

Technical characteristics of the ADC:

Static

Zero displacement error - The value of the input signal at which the output code of the ADC is zero.

Error of full scale - relative difference between the real and ideal values \u200b\u200bof the transformation scale limit in the absence of zero offset.

Nonlinearity - maximum deviation of the real characteristic of the conversion D (U (T)) from the optimal

Dynamic

Conversion time - This is the time counted from the beginning of the sampling pulse or the start of the transformation until the sustainable code appears corresponding to this sample.

Practice

The classic diagram of the parallel analog-to-digital conversion in a simplified form looks like this:

Resistors shares the reference voltage in equal proportions. The references of the analog signal and part of the reference voltage are fed to comparators, where they are compared. In the case of coincidence at the output of the comparator, we have a logical unit. Thus, it turns out the code that the encoder converts to the required format.

• Gorovsky I.S. Radio engineering chains and signals.
• Baskakov S.I. Radio engineering chains and signals.
• Kester Walt. The Data Conversion Handbook.

P.S. The article implies the equality of concepts function and signal.
P.P.S. The level of the article is designed for a wide audience.

Tags: signal, spectrum, quantization noise, quantization, discretization, comparator, ADC, analog, digit, encoder, digitization, quantization step, ADC

In electronics, signals are divided into: analog, discrete and digital. Let's start with the fact that everything that we feel we see, for the most part is an analog signal, but what sees the computer processor is a digital signal. It sounds not entirely clear, so let's deal with these definitions and so as one type of signals is converted to another.

In the electrical representation analog signal, judging by its name, is analogue of a real value. For example, you feel the ambient temperature constantly, throughout life. There are no breaks. At the same time, you feel not only two levels "hot" and "cold", and an infinite number of sensations that describe this value.

For a person, "cold" can be in different ways, it is autumn coolness and winter frost, and light frosts, but not always "cold" is a negative temperature, as well as "heat" - not always positive temperatures.

From here it follows that the analog signal has two features:

1. Continuity in time.

2. The number of signal values \u200b\u200btends to infinity, i.e. An analog signal cannot be accurately divided into parts or chanting, breaking the scale to specific sections. Measurement methods are based on a unit of measurements, and their accuracy depends only on the price of dividing the scale than it is less, the more accurate the dimension.

Discrete signals - These are signals that represent a sequence of reports or measurements of any value. Measurements of such signals are not continuous, but periodic.

I will try to explain. If you installed the thermometer somewhere, it measures the analog value - it follows from the above. But you, in fact, watching his testimony, receive discrete information. Discrete - it means separate.

For example, you woke up and learned how many degrees on the thermometer, the next time you looked at it on a thermometer at noon, and the third time in the evening. You do not know how fast the temperature changed, evenly, or a sharp jump, you know only the data at that time that was observed.

This is a set of levels, type 1 and 0, high and low, or not. The reflection depth of information is in digital form is limited by the digital device's digit (logic set, microcontroller, processor etc.) It turns out that it is suitable for storing boolean data. An example is the following, for the "day" and "night" type data storage, is enough of 1 bits of information.

Bit- This is the minimum value of the information presentation in digital form, only two types of values \u200b\u200b1 can be stored in it (logical unit, high level), or 0 (logical zero, low).

In electronics, the information bit is represented as a low voltage level (close to 0) and a high voltage level (depends on a specific device, often coincides with the supply voltage of this digital node, typical values \u200b\u200b- 1.7, 3.3. 5V, 15V).

All intermediate values \u200b\u200bbetween the received low and high levels are the transition region and may not have a specific value, depending on the circuitry, both the devices in general and the internal circuit of the microcontroller (or any other digital device) may have a different transition level, for example for 5 -tolt logic for zero, voltage values \u200b\u200bcan be taken from 0 to 0.8V, and per unit from 2V to 5V, while the gap between 0.8 and 2B is an uncertain zone, in fact, it is separated from its help from one.

The more accurate and capacious values \u200b\u200bneed to be stored, the more you need a bit, we give a table-example with a digital form display of four days of time:

Night - Morning - Day - Evening

For this we need 2 bits:

In the general case, the analog-to-digital transformation is the process of translating the physical value into a digital value. The digital value is a set of units and nozzles perceived by the processing device.

Such a transformation is necessary for the interaction of digital technology with the environment.

Since an analog electrical signal repeats its form input signal, it cannot be written in digital form "as there is" because it has an infinite number of values. An example can be given a sound recording process. It looks like this in the primary form:

It is the sum of waves with different frequencies. Which, when decomposition in frequencies (for more details, see the Fourier transform), one way or another can be closed to a similar picture:

Now try it in the form of a set of type "11110001010100", quite difficult, isn't it?

Another example of the need to transform analogue value into digital, is its measurement: electronic thermometers, voltmeters, ammeters and other measuring instruments interact with analog values.

How is the conversion?

First look at the diagram of the sample conversion of the analog signal into digital and back. Later we will return to her.

In fact, this is a complex process that consists of two main stages:

1. Signal signal.

2. Quantization in level.

Signal sampling is the definition of the time intervals on which the signal is measured. The shorter these gaps are, the more accurate measurement. A period of sampling (T) is called a segment of time from the start of reading data to its end. The sampling frequency (F) is the reverse value:

After reading the signal, it is processed and saving into memory.

It turns out that during the time that the signal readings are read and processed, it may change, thus, there is a distortion of the measured value. There is such a Kotelnikov theorem and derives such a rule from it:

The sampling frequency must be at least 2 times more than the frequency of the discretezed signal.

This is a screenshot from Wikipedia, with an excerpt from the theorem.

To determine the numerical value, quantization is required. Quantum is a certain gap of the measured values, averaged the above-mentioned number.

Those. Signals from x1 to x2, conditionally equal to a specific XY value. It reminds the price of dividing the arrow measuring instrument. When you take reference, you often equal to the nearest mark on the instrument scale.

So with quantization in terms of level, the more quanta, the more accurate measurements and the more signs after the comma (hundredths, thousandth and so on) they may contain.

More precisely, the number of signs after the comma is rather determined by the discharge of the ADC.

The picture shows the process of signal quantization using one bit of information, as I described above, when a high level is taken when a certain limit is exceeded.

On the right shows the quantization of the signal, and the recording in the form of two data bits. As you can see, this fragment of the signal is already divided into four values. It turns out that as a result, the smooth analog signal turned into a digital "step" signal.

The number of quantization levels is determined by the formula:

Where n is the number of discharges, N is the level of quantization.

Here is an example of a signal broken into a larger number of quanta:

From here it is very clear that the more often the values \u200b\u200bof the signal are removed (more sampling frequency), the more accurate it is measured.

This picture shows the conversion of an analog signal into a digital view, and to the left of the orphan axis (vertical axis) record in a digital 8-bit form.

Analog-digital converters

ADC or analog-to-digital converter can be performed as a separate device or to be built-in.

Earlier in microcontrollers, for example, the MCS-51 families did not contain an ADC in their composition, an external chip was used for this and there was a need to write a routine of processing external IS values.

Now they are in most modern microcontrollers, such as AVR ATMEGA328, which is the basis of most popular, it is built into the MK itself. In ARDUINO, reading analog data is carried out simply - the Analogread () command. Although in the microprocessor, which is installed in the same no less popular Raspberry Pi it is not, so it's not so unequivocal.

In fact, there are a large number of options for analog-digital converters, each of which has its drawbacks and advantages. To describe which within this article does not have a special meaning, as it is a large volume of material. Consider only the general structure of some of them.

The oldest patented ADC option is PAUL M. Rainey, Facsimile Telegraph System, U.S. Patent 1,608,527, Filed July 20, 1921, Issued November 30, 1926. This is a 5-bit ADC direct conversion. The names of the patent come thoughts that the use of this device was associated with the transfer of data through the telegraph.

If we talk about modern ADC direct conversion have the following scheme:

It can be seen that the input is a chain that is given a signal at the output when crossing a threshold signal. This is the discharge and quantization. Who at least a little strong in circuitry, saw this obvious fact.

Who is not strong, the input chain works in this way:

Analog signal enters the "+" input, on everything at once. The outputs with the designation "-" comes the reference voltage, which is unfolded using a chain of resistors (resistive divider) on a series of reference stresses. For example, a row for this chain looks like this ratio:

Urefi \u003d (1/16, 3/16, 5/16, 7/16, 9/16, 11/16, 13/16) * uref

In brackets through the comma, it is indicated which portion of the total reference voltage UREF is fed to the input of each input voltage.

Those. Each of the elements has two entrances when the inlet voltage is familiar «+» The logical unit appears at its output, the logical unit appears at its output. When on a positive (non-converting) input, the voltage is less than on a negative (inverting), then at the output - zero.

Voltage to share in order to break the input voltage to the desired number of discharges. When the voltage is reached at the input at the output of the corresponding element, a signal appears, the processing circuit displays the "correct" signal in digital form.

Such a comparator is good for data processing speed, all elements of the input chain are triggered in parallel, the main delay of this type of ADC is formed from a delay of 1 comparator (still work in parallel) and the seer delays.

However, there is a huge lack of parallel chains - this is the need for a large number of comparators, to obtain high-bit ADCs. To obtain, for example, 8 digits, you need 2 ^ 8 comparators, and these are as many as 256 pieces. For a decade (in Arduino, 10-bit ADC, by the way, but another type) you need 1024 comparator. Judge themselves about the feasibility of such a processing option, and where it may be needed.

There are other types of ADCs:

sequential approximation;

delta Sigma ADC.

Conclusion

Convert analog signal into digital need to read parameters from analog sensors. There is a separate type of digital sensors, they are either integrated chips, for example DS18B20 - on its output already digital signal and can be processed by any microcontrollers or microprocessors without the need to use the ADC, or an analog sensor on the board on which its converter has already been placed. Each type of sensors has its pros and cons, such as noise immunity and measurement error.

Knowledge of the principles of the transformation is necessary for all who work with microcontrollers, because there are no such converters in each modern system, such converters are built, you have to use external chips. For example, you can bring such a fee designed specifically under the Raspberry PI GPIO-connector, with precision ADCs on ADS1256.